Panasonic OIS compatibility on Olympus bodies?

I shoot with an EM1.2 + 12-100 Pro as my main combo. Of course the dual IS is stunningly good. But really IS of any type is mostly useful in low light when shutter speeds are slower, and to allow lower ISO, especially at longer focal lengths. But, back in my 35mm film days, IS only became available in the last few years. In fact I got my first stabilised lens just before I took my last film photos about 15-16 years ago. Until then, like everyone else we simply user the shutter speed to focal length ratio and it worked fine. Although we didn’t pixel peep prints so critically then either.

TL:DR: Does IS really make that much of a difference for most photography that we should worry about compatibility?

My thoughts, and I offer this purely as comment, I’m not saying I’m right or that others’ don’t have valid points to make:

With few exceptions, lenses and bodies released about the same time seem to be relatively compatible especially of the same brand. And again with few exceptions, the newer bodies seem able to take advantage of lens IS if it’s available. Nowadays, with such effective 5-axis IBIS as on the latest Olympus and more recent Panasonic bodies, lens IS seems less important IMO. Nice if dual IS is available, but hardly critical. Do we really take that many photos at 1” shutter speeds hand held? They’re more likely to be travel snaps than something critical that you’d want to print a 30x20”. For those you’re more likely to use a tripod or similar anyway.

Acknowledging that the thread is about cross-manufacturer lens compatibility, μ4/3 is now more about the mount than total compatibility isn’t it? I mean, why should one company restrict what they see as their advantage take a back seat to cross-brand usage? Panasonic clearly has been the leader in lens OIS while Olympus sees IBIS as it’s solution. And even then, I think Panasonic’s widest prime lens with OIS is the 42.5mm. Under that you get no IS unless using a later model with IBIS or an Olympus. All that said, I am sure that both manufacturers have released bodies at times with features that “encourage” the purchase of their lenses. And that goes for all systems. In 50 years of photography, I’ve almost without exception found I get the best results with a native brand lens. Some love their Sigmas and no doubting they have some incredible glass for the prices, but they rarely have 100% compatibility with the body they’re mounted on either.

In my view, IS is at best 10-20% important. And that is when I’m using a long focal length without a tripod.